GearScout has photos of SIG Sauer's attempt at Army's Handgun Modular System. There are several changes compared to commercial P320
http://blogs.militarytimes.com/gearscout/2014/10/13/sig-sauer-p320-mhs-edition/
Edit: More info from Soldier Systems
http://soldiersystems.net/2014/10/21/sig-sauer-gives-us-look-modular-handgun-system-candidate/
From: Gear Scout, Soldier Systems